I would not get anything now. First I would use it to see what is truly useful and not. I definitely would not rush in to new tires it is totally unnecessary. You will probably not use it during the winter and that will be plenty of time for the upgrades you really want and need.
The best advice is to do a very very thorough inspection with the dealer and this should take hours not minutes.
In the RV ownership game it's very easy to let yourself be convinced to buy and do a lot of things that are costly and totally unnecessary. Especially on this site. Take a step back. Patience is your best friend in this kind of stuff. Mods I thought at one time were very desirable have over time faded to unimportance the more I use the vehicle and I find what is truly needed.
